1. Field
The present disclosure relates to capacitive deionization electrode materials, capacitive deionization electrodes and apparatuses including the same, and production methods thereof.
2. Description of the Related Art
In some parts of the world, the water supply may include a relatively large amount of minerals. For instance, in Europe, limestone is frequently found in groundwater. Thus, tap water in these regions may contain a relatively large amount of minerals. Water having a relatively high mineral content (i.e., hard water) may cause problems, including frequent occurrences of lime scale in the interior walls of pipes and decreases in energy efficiency when such water is used in home installations such as heat exchangers and/or boilers. Moreover, hard water is inappropriate to use as wash water. As a result, an appropriate technology is utilized for removing ions from hard water to make it into soft water, in particular, in an environmentally friendly manner. Furthermore, the use of seawater desalination to obtain water has been increasing as larger and more populated areas begin to experience water shortages.
A capacitive deionization (CDI) apparatus is a device that applies a voltage to porous electrodes having nano-sized pores to provide them with a polarity. As a result, ionic materials are adsorbed from a medium, such as hard water, onto the surface of the electrodes, thereby removing the same therefrom. In the CDI apparatus, when a medium containing dissolved ions flows between two electrodes of a positive electrode and a negative electrode and DC power having a relatively low potential difference is applied thereto, the anionic components and the cationic components among the dissolved ions are adsorbed and concentrated onto the positive electrode and the negative electrode, respectively. When an electric current flows in a reverse direction between the two electrodes by, for example, short-circuiting the two electrodes, the concentrated ions are detached from the electrodes. Since the CDI apparatus does not require a high potential difference, its energy efficiency is high, toxic heavy metal ions may be removed together with the hardness ions, and its recycling process does not need any chemicals. In order to efficiently operate the CDI apparatus, it is desired to develop an electrode material capable of exhibiting enhanced deionization efficiency.